To study the health effect of air pollution, measured as particulate matter greater than 10mm in diameter (PM10), we analyzed the effect of daily hours of exposure on the number of urgency admissions for acute bronchitis, adjusting for temperature and humidity on the same day. The study was conducted in six regions of Santiago, Chile, during the winter of years 2002 to 2004, for infants and elders. The delay between pollution time series and disease was modeled using a polynomial distributed lag (PDL) function included in a generalized linear model. The linearity assumption was evaluated using a smooth-spline model approach. The highest effect for exposure to PM10 was detected with 4 days of delay. For both groups, the effect of temperature was linear, but that of humidity was not. Air pollution effect varied according to level of exposure and geographic region, increasing by 3% the total number of infant emergency consultations for each hour of exposure to levels greater than 150µg/m3. The study thus showed a significant impact of air pollution on population health.